Tasker Developer Note: in Android 2.0+, the Keyguard action should probably not be used unless the display is *on* and *unlocked*, so try this profile at your own risk.

This "Recipe" will duplicate the function of a program on the market called "Autolock"

It turns the keyguard off after unlocking and turns it back on after the screen has been off for a set amount of time

You need to add two Event Profiles

click New and select Event

select Display then Display Unlocked

Select Priority Normal

click + in the bottom left to add an action

select Display and then Keyguard

change dropdown to Off

click Done

click Done

click New and select Event

select Display and then Screen Off

select Priority Normal

click + in the bottom left to add an action

select Tasker and then Wait

change Minutes to 1 (or 30 seconds or whatever you want)

click Done

click + in the bottom left to add an action

select Display and then Keyguard

change dropdown to On

click Done

click Done

When you unlock your phone the keyguard will turn off.
When the screen turns off you can still wake the phone without the lock screen for 1 minute (or whatever you choose)

Alternative way

The above combination of two scripts may re-enable Keyguard if you turn on the phone again within the 1 minute time span. This way, the Keyguard off-Event will fire while the Keyguard on-Event is still waiting and finally turning it on again.

To be able to handle this situation, we have to cram everything into one event, like this:

click New and select Event

select Display and then Display Unlocked

keep Priority at Normal and click Done

click + in the bottom left to add an action

select Display and then Keyguard

keep the setting at Off, click Done

click + again

select Tasker and Wait Until

set Seconds to 30 (this is the interval, Tasker checks for the condition set in next step)

further down in the Until field enter %SCREEN into the left field (or use the Label-button in the top right, you have to scroll up to reach it)

click the ~ button and select Matches

in the right field enter off

click Done

now add another action: click +, select Tasker and Wait (not Wait Until this time!)

set it to 2 minutes (or however long it should take to re-enable Keyguard)

click Done

finally add another step: click +, select Display, then Keyguard

change the setting to On, click Done

to add the "magic", so that Keyguard stays off if you use your phone again within the time limit, open the Task Properties by clicking on the Screwdriver/Wrench-button in the bottom right (left of the help button)

at Collision Handling select Abort Existing Task

click Done

click Done

click Apply

Now when you unlock your phone, the task will run and will turn Keyguard off. Then it will check every 30 seconds whether the screen is turned off. If it is, it will wait 2 minutes and finally turn keyguard on again. If you unlock your phone in these 2 minutes, the currently running task will be cancelled and a new one will be started.